Telephone system



Mairgh 19, 1929. R. MERCER Er AL 1,705,834

TELEPHONE SYSTEM Original Filed Aug. 16, 1924 7 SheetsI- Sheet 1 I R hm Imrenlfir Richard FIEPBEP -FParLZ Teach March 19, 1929. R, MERCER ETALV TELEPHONE SYSTEM Original Filed Aug.16, 1

7 Sheets$heet 2 Emhard PIsm: Q-Frank .Tsnuh MWHU";

March 1-9, 1929. R. MERCER ET AL. 1,705,834

' TELEPHONE SYSTEM Original F ilec l Aug. 16, 1924 7 Sheet-Shet 3 ILEFEITH Richard Mama-Frank TE'Z'ZE.

March 1929- R. MERCEVR ETAL 1,705,834

I TELEPHONE SYSTEM Original Filed Aug. 1 1924 7 Sheet-Shet 4 EwhaPd NamaP- Pafik TEnUZ'L 'Mamh 1929. R. MERCER ET AL I 1 TELEPHONE SYSTEM Original Filed Aug. 16, 1924 7 Sheets-Sheet 5 Irmm=- Richard Mercer "-FPETLk T511021 7 Sheets-Sheet e R. MERCER ET AL TELEPHONE SYSTEM Original Filed Aug. 16, 1924 March 19, 1929.

. [W I Emhafid NEMEP 1 al: T522022 March 19, 1929. R, MERCER ET AL 1,705,834

TELEPHONE SYSTEM Original Filed Aug. 16, 1924 7 shee c-snet 7 Ewhard meme flank Tenuh PatentedMar. 19,-

I i I I. i I I I V UNITED A STATES" PATENT or E l-c ENGLAND, ssrenons, IBY ransnn assrenmrm'rs; To aurorrarrcfnnnornrc me,

or crrrcaeo, rLLrnors'A conroaerron or pnnawnnn' "we eow: S E 1 Application filed August 16, 1924, ser a1no .'7a2,355, and in Great Britain September 18, 1923.

1 Renewed May19, 1928;. i I I i v I;

RICHARD MERCER, or n w, AND FRANK. Taiwan, on WEST nonwoon, 11015119011,

The'present invention concerns improvewhen operated todisconnect the normal set ments in or relating to, telephone systems and of wipers and connect up the second set, the 5 more particularly arrangements for more remainder :Oflt'he control being-effected ir'om economically laying out exchanges than has the register translator. j y

5 hitherto been practised. Further the inven According to one feature of the invention tion relates toimprovements in telephone sysin a telephone system; employingregister tems using .step-by-step switches of the translators, controlling arrangements for 'ef- Strowger type having two directions of movefooting the translation are modified 'insuch-a ment. It is well known that such switches as manner that switching currents are 'adapted;

m usually employed are arranged to. have 10 to het'ransmitted in addition to series of step- I steps in one direction and 10 steps in the other ping impulsesl The expression stepping im- I direction making a total of 100 contacts availpulses. will be. understood to mean impulses able. It has also been proposed to use a numof the ordinary type such as circuit interrupber of sets of wipers so that the capacity or" tions tor operating 'step-by-step switches, such switches. can be increased \vithoutlmate- .Whil'B the term;fswitchingcurrents? is to be I .rially afliecting the constructional details, and taken to mean special currents transmitted I the object'of the invention more particularly over the line for effecting a switching operaconcerns arrangements for more economically tionwhich will in general be changing over using or arranging the standard type oftrom one setofwipers to another, but ma j 20 switches whether with one or more sets of alsocbe taken. to include changing over from wipers so that they can be controlled an one switch to another. I

impulse sender of the standard type capable I According to another feature of the inyenof generating up toilO impulses for each option in a telephone system employing register oration thereof, l I V translators, in addition to the translationoil Previously in arrangements proposed for the portion of the member comprising theex. laying out a system employing Strowger type change designation of a called party, a trans switches more economically than is usual with lation is also eflj'ected of the numerical desigthe ordinary decimal systeimit has been nec nation into a combination of stepping im- 7 essary eitherto provide special dial switches pulses and switchingcurrents. I I so or special controlling mechanisms for the A'further feature of the'invention is that switches,either of which alternatives necessia. device in the register translator responsive V I .tates a considerable departure from standard tothe'idialling of a certain exchange or ex practice in the construction of the apparatus changes determines whether the switches in concerned." In one arrangement however it such exchanges are tobeset by stepping im I 35 has been proposed to use large capacity pulses corresponding to thosedialled it switches in-which. there was more than one calling party orjwhe'ther atranslationo'f the means of access to the switch and arelay 'conimpulses dialled is to be efiec je'd.

nee ted in the testxconductorof-one of .the Still another feature of the invention is, the means ofaccess, when operated, switched over provision of aplurality of means for trans- 40 one set of normally connected wipcrsandim lating the impulses corresponding to the 1111- I serted a second, set of wipers of a large camerical designation of the wanted'party, the pacity switch. A feature of the presentinparticular translating means, it any, which is vention is that a registertranslator 15 emen' ployed, -bein-g determined'in accordai'ice ployed for converting'the impulses dialled by with the exchange; required. The means em- 45 a calling party into a combination of switchployed may be such that When the register has ing operating impulses and relay. operating recorded a particulardigit or digits, the imimpulses or switching currentsso that the pulse sending device is so controlled thatione 10o switching over of the wipers takes place inde or the digits stored is not transmitted. This pendently of the switch operating impulses permits the number of switching stages in the 50 The only modifications contemplatedto the required exchange'to be reduced below that switches themselves consists of providing an corresponding to the number'ot digits ,infthe additional set of wipers, an additional bank numerical== designation T of the wanted sub-'10s of contacts and a switcl'iing relay adapted scriberesincethe necessaryselection corra known typeand therefore not shown. hen

sponding to the digit which has been suppressed is taken care of by suitable wiper selection of theiswitches employed.

These and other features not specifically mentioned atthis point will be better understood from the following description taken in conjunction with the accompanying drawings. It will be understood however that the particular arrangement illustrated is given by way of example only and that various modifications in the circuit details could be made by those skilled in the art without departing from the spirit of the invention.

It will be assumed inthe description that all the switches employed have only two sets of Wipers, since up to the present this is the maximum number which has been successfully employed in practice. The invention, however, must not be considered as limited to two sets of wipers as theoretically there does not appear to be any reason why three sets or more could not be used. The particular objection is that owing to the additional power required for operating the switch, particularly on the rotary movement, it would probably be necessary to re-design the operating magnets, and this would necessitate a considerable departure from the apparatus used at present. It is an important feature of the. present invention that the apparatus employed should as far as possible diti'er so slightly from existing apparatus as to ensure that there is no departure from principles already well established in practice. a

Referring now to the drawings comprising Figs. 1-6, these show by means of the usual circuit diagramssutficient of the apparatus to enable the invention to be understood. The general arrangement is very similar to that shown in the British patent specification No. 194,580 and the alterations which have been made from the circuits shown in that specification are such as still to permit'the normal working to be carried out as therein indicated. The invention will be best understood if the normal working is first described briefly and then the different operations which take place when calls are set up to ex changes in which the novel features of the in vention are applied.

Srugpose in the first instance that a subscriber in the Western exchange wishes to call another subscriber whose number is TORington 23435 he will. therefore first dial the letters TOR and then the numbers 23 15. Assume further that the first selector trunk l) extend .ing to the selector E shown in Fig. 1 is seized over the contacts 22, 23, and 24 by the ca lling partys primary line switch which is of well the line switch switches through a circuit is complete-d for the line relay 6 1- of the register selector F associated with the first selector trunk D and this relay at armature 72 eompletes a circuit for release relay 65. At armature 73 prepares the impulsing circuit. The operation of relay connects earth at armature 75 over lead 63 to release trunk conduc tor 11 so as to, maintain the subscribers line tion of magnet 69, the wipers to 88 in-' elusive of the register selector F are raised four steps, while the relay 66 remains energized throughout the train of impulses. -When the off normal contacts 78 close upon the first step out the switch, a circuit is completed for stepping relay 67 in the usual man'- ner and when the normally closed contacts controlled by armature 7 7 again make on the de-energization of relay 66, a circuit is com pleted for the rotary magnet 70 so that the switch commences to hunt in known manner. lVhen an idle register translator in this group is found, there will be no earth on thecontact with which wiper 87 is then in engagement so that relay 68 will no longer be short circuited and will consequently operate.

Thereupon at armatures 81 and 82 a circuit" is completed, for line relay 30 of the selector E extending as follows: battery, upper winoing 01 relay 30, back contact and armature 40, upper trunk conductor, normally closed springs controlled by armature 14, lead 25, front contact and armature 81, wiper-85, contact 89, lead 100, back contacts and 'arma't-ures 120 and 123 in parallel, armature 187 and its back contact, lead 101, contact 90, wiper 86,

armature 82 and its front contact, normally closed springs controlled by armature 18, lower trunk conductor, armature 43 and its back contact, lower winding oti'elay '30, earth. By the operation of relay 30,

31 is energized and the selector E is prepared. tor operation in the usual manner. Relay moreover at armature 84 completes thein'r,

pulsing circuit over wiper 88 and at armature 8e completes a holding circuit by con necting earth over wiper 87. The connection 01" earth from armature 74 extends over 'lrontcontact and armature 8 1, wiper 87, contact 91, lead 1 normally closed springs controlled by armature 125,.arinature- 12? and its back contact to lead 203. This earth there-- tore energizes relays llOand 111, the tormcr by operating armature 130 serving to prevent the release of the connection, while the latter at armature 132 opens the circuit for restoring the sending switch S to norn'ial and at armatures133 removes earth, from leads 160, 161, 162 and, 163, sons to open the circuit for restoring the sequence switch S to normal. The connection of earth'to lead 206 and 2" 203; also has the effect ol energizing relay 210 which by operating its armatur'e217 pre' pares clocking c1rcu1t for relay 205, an at armature 209connects up a timingdevice '1 which is providedfor preventing the register translator remaining in'use indefinitely as willbe explained later. i

"The subscriber will now dial the second .e'tter O in consequence or. yhich ten intern )tions will be produced in the circuit 01 inc relay 6 1 and it will release its armaure 73 acorresponding number of times. Each time armature Y3 engages its haclreoin tact the following circuit is completeo :Cearth,

front contact and armature 7 1, back contact and armature 73, armature 83 and its front contact, wiper 88, contact 92, lead'103, armatare-136 and its back cont-act, lead 202, winding of relay 20. wiper. 218 of the master switch M infirst position, lead 801, winding of ve'tical magnet 803 otthe register switch I to battery. Relay 207 is energized throughoutthe train 01" impulses and at armature completes acircuit for relay 208 which is also made slow to release. At, the endot the train.

of impulses after relay 207 releases, aCircult is momentarily completed from earth, armature 215-and its back Contact, armature 216 and its front contact, winding of stepping magnet 212 to battery; the wipers 218 and 219 of moved on one step into their second position.

The subscriber will now (:lialthe third letter ltwhereupon two impulses will be repeater. by relay 6-1 over a circuit whlch extends as previously traced to wiper 218 and thence over lead 802 to the rotary magnet 30 1 of the register switch 3. By means of these two series of impulses the switch Jis operated to the second contact in the tenth level and l e letters OB. are thus registered. the end of the train of impulses representing the letter R, the master switch 1 is moved on one step as before into 'its third position ant is then in a condition to record the first nu inerical digit on the thousands register M.

lhe circuit. over which these two impulses.

are sent is as before wiper 218 and then through the winding; of relay 281, winding of let 227 to bath-sky. -the first digit 1 c. thus mire-need into engagement with the second contacts in their respective banks. livelay 22-31 is operated throughout the, rain of impulses and at armature removes earth connected up over oil normal contacts from lead 4121 so as'to prevent the premature sending of impulses as will be more fully appreciated subsequently. ner the next digit 3-diallcd by the subscriber stepping m: The wipers is upon the hundreds register M the I next digit 1 on the tensdigit'register M and ter h.

the fourth and last digit on the units regiss As soon howeverfas themaster witclrM nrst closes the master switch M are therefore I I sier M are.

In .a similar man- 7 reaches its third position, that is to say imi edlately allthe exchange selecting digits havebeen stored, acircuit was completed terminal'Sl on the left-hand side of the intermediate distrihutin frame hereafter .re-

- I 2* i 1 terred to as the I. D. r umper to nus-bar ,6, lead to the eilgl'it-h: contact in the bank of wiper 114: of the sending switch S, and this eai 'th'serves to determine the numl'zer of impulses tobe When the interrupter 1 its contactsatter the shore traced circuit has been completed, "relay 1.0" e'ncrgizes and at its armature 123 opens: point in the loo 3 across leads 100 and 101 thouc'h' feet the. loop this operation is without e1 is maintained over armature 120 and 'ts baclt contact. Relay 107 also at armature 12% completes a circuit for the stepping magnet 115 of the switch 3 which is arranged to advance the wipers, 113 and 114; on release.

When the interrupterl next breaks the circuit, relay107 ale-energizes and opens contact 12%, whereupon magnet 115 ale-energizes advances wipers. 114: and 118 into engagement with the succeeding contacts in their respec tire hanks. A circuit is then completed from earth, second contact in the bank of wiper 118 and said winenwinding of relay. 106 to bat-- tery. Relay 106 uponoperating, atarniature 1 120, removes the shunt around armature 123 so that theloop is then under thesolecontrol of lllllS armature, at armature 121 prepares a iloclrin circuit for rela 105. at armature 457 disconnects lead l55lrom lead 100, and at armature. 122 completes a circuit over lead.

l-26from the stepping magnet 4:02 or the sequence switch S, which magnet is also arranged to step on release.

\Vhen relay .107 next energizes, the loop ere t'cndi E opened et'armaturc lQZ-Sand the circuit of magnet 115, is again completed. hen relay 107 (lo-energizes,

of operations continues until wiper 114; reaches the eighth contact in its bank to which it will be remembered earth is connect- .ed'from wiper 219 of the master switch MC over lead As soon wiperll-l reaches this contact, at wln chtnne SiX lnterruptions will have been produced by armature 123 in 3 the outgoing loop, a circuit 18 completed from earth over, lead 866 as previously traced,

to the. line b0 of the selectorv V wipers 113 and 114-? are. again advanced one step and this sequen ee wiper 11 i, winding; of relay to battery. Relay 105 upon energizing, at armature 11G completes a circuit over wiper 113 for automatically restoring the sending switch S to its home position, at armature 1.17 completes a locking circuit for itself, at armature 118 opens the circuit of magnet 402 of the sequence switch S at arniz ire 119 opens the circuit of the impulsing relay 10i' and a t armature 4:56 agrai nconnects lead to V-lhcn magnet releases, the wipers at o, 10 1, 105 and 4-06 of the sequence switch S are acvanccd into engagement with the next contacts in their respective banks, in preparation for the sending of the next series of im- 1 es. Vi hen the send switch S reaches in l Ab. it

no maintained after short interval.

l i hen both relays 105 and 106 have released the circuit of the relay 10'?' again completed over the same circuit as previously traced except that wiper 4l05 is now in position 2 and the sending of a further series of impulses con'imences. The control circuit now extends as follows: earth, wiper 210 in any one of the positions 3-? according to the speed which the calling subscriber operates his dial, lead 400, wiper 404-, of the sequence switch S in second position, lead 412, wiper 307. of the switch J and the contact with which it is in engagement, terminal 34 on the left-hand side of the l. D. F. jumper to bus bar 5, lead 365 to the seventh contact in the bank of wiper 114 corresponding to the sent ling of five impulses. The sending switch S therefore operated under the control of the interriupter l in. the manner pre- .'iously described, and after five impulses have been sent over the outgoing trunk conductors to operate a selector similar to the selectcu' E", relay 105 will be energized. This then operates to stop the sending of impulses, to effect ti 3 return of the switch S to its normal position, and to cause the sequence switch and the relay releases 'S' to be moved into its third position.

The earth for controlling the number of i ipulses which shall be sent, now extends over the previously traced path towiper 40 i, thence over lead H8, wiper 308 of the switch J and the contact with which. it 's in engagement, terminal 339 on the left hand side of the l. l). l1, jumper to bus-bar 4, and by way of lead 2-364; to the siJth contact in the bank of 114-. Accordingly the third digit ...ii .*h now transn'iitted by the sending switch 5% is a series of four impulses which will operate the succeedinp' selector in the usual manner. The energizing circuit for relay l07'extends before except that it now over the third contact in the bank of wiper 405. At the end of this train of impulses the sequence switch S is moved on into its fourth position whereupon a circuit is completed as follows: earth, wiper 219 in an (m0 its normal. position, the circuit for relay is one of positions 3'Z, lead 1-00, wiper 40% of the sequence switch S in fourth position, lead 414-, wiper 300 of the switch J, terminal 338- on the left hand side of the I. D. F. jumper to terminal X on the right hand side, lead 3'70, third contact in the bank of wiper 03 and said wiper, through the interrupter contact to ma not 402. The wipers of the sequence switch 5% are thus moved on a further step and circuits are prepared for sending the first ninnerical digit. Thus the effect so far has been that the letters TOR representthe digits 402 have been converted into the digits 054; which have been sent out to select the Torrington exchang 7 Since the which is now being considered is that of a connection to an exchange arranped on the. ordinary decimal principle, the nim'ierical digits will not be translated but will he retransmitted exactly as dialled by the calling; .bscriber, It will be assumed that the subscriber is dialling at an'average rate, and that by this time he has dialled the hrst two ninnerical digits. A circuit is now completed therefore, over the operated off-- norn'ial springs 236, arn'iature 2'35 and its back contact, lead 421, fifth contact in the bank of wiper 405, and said wiper, lead 4-25, and over the previously traced circuit "through the inmulsing relay to battery by way of the I rrupter L- l he contact in the bank of wiper l 14 corresponding to the required number of impulses in the train i. e. 2, is now mark-ed over the following circuit: earth, wiper 210 in position 6, lead 100, wiper 40-1, lead e15, wiper 244. of the thousands register ltl and the second contact in its bank, lead 472, armature 50 i: and its back conta to the fourth contact in the bank of wiper. 'llhe sending switch therefore operates 1 the manner previously described to send a train of two impulses which will operate a thousands selector in the l orrington exchange.

ll hen the marked wiper 11-4, relay105 previously described inc of the next digit cont ct is reached by is energized with. the results, and the sendcominences, the deterct, lead llt) mining contact being: new marked over the wiper 40% in sixth position and wiper 2 h) of the hundreds register hi In a similar manthe tens digit .1- and the units digit 5 are sent out to operate the connector at the de-V sired excl]: nge. 7

After these digits have been sent the sequence switch r" is moved on inv the usual manner into s ninth position and a circuit may now he raced as follows: eartn, wiper 4310c and the ninth contact in its bank, lead 1L0 0, normally closed springs controlled by armature winding or relay 112 to battery. Pcla 112 thereupon operates, conipletes a locking circuit for itself at armature 139 at armature 137'inserts a resistance 1 11 in the line loop to prevent the subscribefis line ,sequcntly a further train of impulses is sent quence switch wipers will .be moved on one step into their fifth position.

A circuit :tordetermining the number of impulses to be sent as the first numerical digit now extends as follows :-earth, wiper 219 in say position 6, lead 400, wiper 404, lead 415, wiper 244 and second contact in its bank, lead 452, armature 504, and its back contact to lead 362 and thence to the fourth contact in the bank'of wiper 114 so as to stop the generation of impulses when two have been transmitted. Upon the termination of this series of impulses, the sequence switch 5*) is moved on as usual and the apparatus is then in condition to effect the generation of a further train of impulses. The remainder of the numerical digits are now sent out exactly as described for the connection to Torrington. Since in this case the first numerical digit was 2, which is sent out exactly as received, it is not necessary to send a discrim- 1 inating impulse over the line to effect suitable wiper selection at the connector; consequently the operation of relay502 is without efiect andthe connection is set up in the usual manner just as if t is switches involved in the connection were all of the normal type.

Suppose, however, thatthe first numerical digit in the wanted subscribers number has been 7 instead of 2; in this case aliter all the exchange digits had been sent, the control circuit would extend from wiper 219 in position 6, lead 400, wiper 404, lead415, wiper 244 and the seventh contacts in its bank, lead 457, armature 515 and its front contact, lead 362 to the fourth contact in the bank of wiper 114, corresponding to a series of two impulses. Thus in this case, the same effect is produced whether the first digit is 2 or 7, and similarly with 1 and 6, 3 and 8, 4 and 9, and

and 0.

In order, however, hat the effect at the distant end may be different according to whether 2 or 7 is dialled, a special switching current is sent in the latter case. .Vhen the digit dialled is '1', as soon as the Wipers of the sequence switch S are advanced after the sending of the second numerical digit, relay 105 being still operated, a circuit may be traced as follows: ti om earth, wiper 219, position 7, lead 400, wiper 404, position 7, lead 417, arma ture 50 9 and its front contact, lead 401, seventh contact in the haul; of: wiper 206 and said wiper, lead 455, front contact and armature 456 to lead 101 extending to the lower talking conductor. This earth connection re mains on over armature 457 and its back contact after relay 105 de-energizes and is only removed when relay 106 again operates immediately prior to the sending of the next series of impulses. V

In order that the purpose of these special arrangements may be fully appreciated it will, at this point, be desirable to describe more fully the repeater and selector and connector switches shown in Fig. 6, the repeater being in the originating Western exchange, while the switches are in the Lotl'lair'exchange. It will be seen from the arrangements at the registertranslator just described that the first selector never has more than five impulses sent to it. In order that the upper halfof the bank may beutilized however the switch is provided with two sets of wipers which are spaced live steps apart and arrangements are made for it to hunt simultaneously over the contacts engaged by both sets of wipers, the line connected with being then the one first found idle by either set of wipers. Corresponding levels i. e. 1 and 6, 2 and 7 etc, are arranged to lead in the same direction so that a group of 20 trunks is obtained instead of the normal 10 and in consequence an appreciable reduction in the number of second selectors may be made. The second selectors involved in the connection are not shown, as they are of standard type, but the position they occupy in the connection is indicated by the dotted rectan gle D.

The connector shown in Fig. 6 is slightly different from the standard construction in that it also has two sets of wipers, but in this case each has access to a corresponding eomplete bank of10 levels. The bringing into use of the other set ofwipers when necessary, i. e. when a first numerical digit less than 5 is dialled iseliected unless one of the speaking leads is momentarily earthed when the switch is taken into use as. above described. This earth is arranged to short circuit the relay for changing over the wipers, so that it does not then operate.

The actual operation of the apparatus, shown in Fig. 6 will now be explained in rather more detail. Dealing first with the repeater B, when th is. is taken into use relays 600 and 601 are energized in series over the normally closed springs controlled by armatures 611 and 612 and the loop closed by arniatures 120 and 123. Relay 600 thereupon at armature 602 completes a circuit for release relay 604 which at armature 605 connects earth to release trunk conductor 599 to maintain the preceding switches operated, and at armature 606 prepares the in ipulsing circuit. Relay 600'also operates armature 613 thereby co1npleting a circuit over trunk conductors 614 and 615 and the left hand winding of relay 610 for the line relay 6 20 of the incoming selector E This on operating, at its armature 621 completes a circuit for relay 622 so that the selector E is prepared for operation in the usual manner.

When a train of impulses isnow sent cortery; relay 608 then by operating its arina= ture 609 short circuits the left hand winding of the shunt iielc relay 616 so as'to improve the iinpulsing. When impulses are repeated by-the opertionof armature 613, relay 620 de-enerp'izes correspondingly andon each de-- ener l-On completes a circuit from earth,

back contact and armature 641, back contact and armature 64:6, armature 621 and its bac'l; contact, armature 623 and its front contact, winding of series relay 625, winding of vertical magnet 650 to battery. By the operation of magnet 650 both sets of wipers are raised two steps and as soon as the oil-normal contacts 627 close, a circuit is completed from earth, front contact and armature 62%, oil normal sorin s 627, front contact and ar-v mature 626, both windings or shunt field relay 629 in parallel, operated oil-normal contact 635, interrupter contacts 63% to battery. Relay 629 therefore operates and at mm, tures 630 and 63lcompletesa locking circuit through both its windings and at armature 632 prepares circuit for therotary. magnet Relay 629 it should be mentioned, is of the shunt iield type andonly operates its arinatures when both its windings are energized by current in the proper direction. Vlhen relay 625 releasesatthe end of the series of impulses, a circuit is completed over the normally closed springs controlled by armature 626 for rotary magnet 633, so that the wipersare rotated one step, the circuit of relay 629 being then opened by the interrupter contact 634. The further operation of the switch depends upon the condition of the lines with which the test wipers 648 and 6&9

ere nowin engagement. 11" both of these wipers-are resting on earthed contacts a circuit is again con'ipleted for both windings of 629, over armatures 639 and 64ldand contacts, so that again operates armature 632 and rotary magnet 683 moves the wipers a further step. This operation will continue as long as both wipers continue to find earth. Suppose now that to. does not; under these circumstances current only flows through one windingof relay 629 am it which has previously been short circuited 'now operates and at its armature 645 opens the circuit of relay 636, at armature 64% complcies a locking circuit for itself. at arma ture 6&6 opens the circuit of the release magnet and at. armatures 643 and 64? connects the speaking leads through to the second so:

t wiper 649 finds earth but test wiper 6&8

cannot operate. Relay 63? however lector D; It should be mentioned that one of the relays 63ifand 636 is adjusted to operate slightly quicker than'the other, so that in the eventof each test wiper coming upon an idle line at the same time, there shall be no doubt as to which line will be taken into use, since each relay on operating opens the circult of the other. T he selector D is standard in all respects and operation therefore need not be described. Fiince it has been assumed that the calling subscriber dialled the digit 7 which has been converted at the register translator into 2, it will be necessary to send a diecriininating impulse whit l eiitected at the register translater in the nmnner that has alreadyb'een described. The eii'ect otthis at the repeater it 13 60 561011; circiut relay 60l whereupon 1t releases and a circuit is completed from earth,

armature 603, and its back contact, armature 667 and its front contact, back contact and armature 669, armature 613 and its front'contact, lower trunk conductor 615, armature and its back contact, armature 64:7 and ltsitront contact, through the selector D" to lead 652, normally closed springs controlled by armature 633, lower winding; of relay662 1 to earth. 7

connection will be on the line whenthe se It should be noted that this earth lector D switches through; consequently relay 622 is short circuited and does notenergize so thatthe set of wipers of the cennector is used. The connection of lead 652 to the winding of relay 6621s broken by the operat1on of armat 663 when release relay 656 operates. In case there had been no earth on the line when the connector was taken into use, relay 662 would have en'er gized in series with the upper winding of line relay 653 and at its armature 667 would have completed a backing circuit-for itself and at its armaturcs 665, 666 and 668 connected up the second set of wipers.

' *ationoi the -su'indard, but may be liricl'ly When the switch is other rcspe described as tollow taken into use, line relay 653 is energized over the loop and thenorinally closed s n-lugs controlled by armature 654; am 6 and either the special earth or the wi of relay 662, and completes a circuit to the release relay 656. Upon the receipt oi? the first of impulses, relay de-enern-izes a corresponding number of times, and on eacli'de 'uiergizntion completes a circuit for the vertical v magnet in series with the Q .ay 65'1", so that the wipers are raised a corres mnding, number of steps. Owing to the shifting of theoiinormal contacts, the next series of impulses is transmitted to the rotary magnet and the wipers are rotated accordingly. When they come to rest and relay .666 tie-energizes, a

busy test is made'by relay 659 and if the required line found idle, the wiper relay 661 'is energized in series with the cut-off relay connector is in all of the wanted s1il'iscrihei"s'lii1e switch. 'lhis latter relay operates its armatures only sufficiently far to clear the called line oi? its normal battery and earth connections, i'nit not to connect up the wipers of the line s witch. Ringing current is then sent out from the ringing generator lit} and when the wanted party replies, the ringing trip relay 058 is operated. The speaking leads are thus switched through, whereupon the hack bridge relay 671 energizes and reverses the current flow back over leads 651 and The flow of current is now in sucl a direction as to permit the shunt field relay ($10 in the repeater it to operate so that at its armature-s ill and 012 it also reverses the current flow back over the connection. This reversal then used for supervision, metering, or like operation ac cording to standard n'actice. The release ot the connection takes place in the usual manner when the calling party hangs up his receiver.

Consider now the case in which a all is to be extended to a subscriber in the Condor exchange which it will be assumed is a coin paratively small exchange of a capacity not exceeding 4000 lines; under these circumstanc s and according to the invention, it is possible to save the first switching stage entirely. This is effected by the use or 19 c capacity switches throughout, each having two sets of wipers and corresponding banks the connectors being similar to those just described in the Lothair excaange, while the selectors are standard except that they have two sets of wipers and means as in the con nector for changing over the wipers. The operation oi these switches is controlled according to the value of the lirst digit by sending discriminating impulses over the line at the appropriate instant in a manner similar to that described tor connections to the Lothair exchange.

Suppose that the wanted suhscrihers numher is (lOlldor 1234; the cal ing subscriber will therefore ait'tor ren'ioviugr his receiver, first dial the letters CON, and then the mum hers 1234. Suppose as in the previous case that he obtains access from his line switch to the first selector trunk l) shown in Fig. 1 and hence that the register selector ll is operated to the fourth level as previously described. Assume further that the switch if then again takes into use the set oi. "'ister translator equipment shown in the (ll':t\'i'l115;.

in response to the dialling oi the letters O and N, the register switch J will be raised to the tenth level as before, and will then be rotated into engagement with the sixth contact in that level. The wiper 219 of the armster switch M being new in its third position, the sending of the exchang 'c code will at once start and it will be seen from the drawing that the cross connections are such that the digits 406 are translated into the digits 348.

through. to terminal 345 on the le tt-hand side of thel. l3. F. and at armature completes a circuit for relay 501. le ay 501 which tl operates, at armature 513 connects earthto lead 440 and at arn'iatures 508, 510, 511 and 512 produces changes in the circui trom the banks of wiper. 205 and 244, the tull importance of which will be more tally understood presently.

hen the exchange selecting digits 34, have been sent out-and sequence switch S reaches position 4, a circuit is completed from earth, wiper 219, lead 400, wiper 404, position 4 lead 414, wiper 309, terminal 342, jumper to terminal X, lead 370, fourth contact in the bank of Wiper 403, interru 'iter connormally closed tact windino' of rotar nia net 402 to batof wiper 403 and saidwiper, interrupter contact and winding of magnet 402 to battery;

the wipers of the s-zequenceswitch S are thus advanced into sixth position. It will be seen.

that the sequence switch wipers have thus passed through the position in which they would send a digit corresponding to the first numerical digit dialled by the calling subscriher, and even if the calling party should. not yet-have dialled the li numerical digit it will be impossiblefor this to be transmitted untranslated. l lo further operatioi'is take place until the second numerical digit has been dialled, this then being re-transmitted to operate an incon'iing lirst selector in the Condor exchange. Since, however, the first numerical. digit is 1, a discriminating earth will have been connected up over the tollowing circuit as soon as the three exchange selecting digits have been sent out; earth, wiper 219 in position 4, lead 400, wiper 404 in sixth position, lead 410, armatu 508 and its Front contact, lead 415, first contact in the bank of wiper 244 and said wiper, lead 451, armature 503 and its front contact, lead 455, arn'ialture 456 and its front contact or armature 457 and 7 its back contact to lead 100. This circuit is also completed over lead 415 when the switch S is in position 5. The eii ect of this earth" circuita relay in the first selector similar to that provided in the connector shown in Fig. 6, so that the normal set of wipers is used.

The train of impulses for operating this selector consists of two impulses which are sent out'in the usualmanner. I 1

When the sequenceswltch againsteps on, ac1rcu1t slmilarto that ust described 1s com-' pleted extending over wiper 404 in seventh position, lead 417, armature 510 and its front of wiper 20,6 and said wiper, lead'455, arm'a 1 ture 456 andits front contact-or armature.

conta-ct, lead 469, first contact in the bank 457 and its back contact to lead100 as'before. This therefore brings about the short cir'c'uiting of a'relay such as 662 in theconnector so that again the normal setof wipers is used. The other digits 3 and 4are then sent out in known manner an'd'the register translator equipment is released as-inthe case previously described' v It will be seen by referringlto-the scheme of connections that if the first digit of the number in the Condor exchange had been 2,

a discriminating:impulse would have been sent to thefirst selector, and consequently'the wipers would not have been changed over,

but that a discriminating impulse would have been sent to the connector so that therefore, the second set of wipers would have'been used; In case'the first'digitis 3, the discriminating earth is used to operate the connector only,

while if the first digit is 4 no discriminating earth at all is'sent so that both'selector and connector employ their second set otwipers; It will therefore be seen that by means of this arrangement, it: is possible to save the' first switching stage entirely by the use of im proved large capacity switches according tothe invention with suitable modificationsin the register translator. clearly also applicable to the case'of a' 2000 or 200 line exchange; in the former case, either the selector or the connector maybe arranged with two sets of wipers.

Y The other arrangements provided-bin the register translator arevery similar: tothose" described in detail'in' the Britishspecification No. 194,580 previously referred to. Forin stance, if the subscriber .wishesto obtain ac-] cess to 'thecomplaint'operatorg 'he will'dial the'l.ettersCOM, whereupon it 'willfbe -assumed he obtains use of'the register translator"equipmentshown, and the switch'J -'after being raised to the tenth level is rotated into engagement with the fifth set of contacts. Inspection ofthe connections at the- I. D. F. will show that'the-translation which takes'place inthis case is intothe digits-6O whereupon switching over is at once eflecte'd- V and .no'nuinerical' digits are therefore sent. 1

and then effects switchingover.

The principle is,

anerical? digit, the register translator may-be released and subsequent digits diall'ed-cby'gu to a specialopcrator who will'then inform of his mistake and instruct him to try again The sending out of the required code may be effected by suitable crossconnections, though if the code comprises more than 3 digits a"7O special code relay must be used, as'nowto' v be described. -j I An information"operator, who will 'probably be located "in another exchange, is reached by dialling the letters INF and as'it, isassumed that levels 1 and 4' of the switch F aremultipled-together, itisstill possible for the register translatorequipment shown to betaken into use. In this case, however," the switch J will not be operated to the tenth "level but to the-sixtlnandit is assumed that on this level connection is made-by the wipers .of the switch J with contacts connected to terminals 346 349, inclusive. 3 A codecomprisin'g the'digitsB, 5 and 3 is first sent out and. when earth is connected to terminal 346' the special code relay'430 is operated. This'by operating its armatures 482, 433, 434 and 435 controls the sending of the further digits 32 v t should be mentioned that the relays'500, 501 and 502 could be provided in common to a number'of exchange codes corresponding to a number of. exchanges in which the spe cial switches. and trunking arrangements were employed. This presents 'no difficulties since theltranslation effected by these relays is a related one in which any particulardigit is always translated in a particular manner a as opposed to the .unre exchange code. i 1 V It hasbeen'assumed throughout the de-': scription that. the'specialarrangements are used only within particular exchanges,"and

that no alteration is made in the normal 'in-' ter-exchange trunkmg. I-t 1s not however 1ntended thatthe invention sho'uld'be thus limited, and it wi'll clearly be quite possible'to employ an improved"trunking scheme'for, trunking between exchanges as 'well as with-- in special exchanges. -Thisiwill mean that two differentexchange code'sdialledby a callingjparty maybe converted into'the sam'e ex; change code for re-transmission -and .callsp routed differently. in; one case in responseto the sending of a switching current or discrim- "inating impulse. From what has already been said, the method of achieving this object will beat once apparent to those skilled inthe 1 H art; probably. the use of an extra Contact 01'1120 the, code relay suitably connected would be I the most desirable solution. It may be men r tionedthat'in' thecircuit shown inthedraw-fi ings the feature 6 isclosed in the British spec iiiication No.194,580 has been omitted whereby if the sender has sent out'the 'full exchange cedefbefore the subscriber dials the first nuv.

calling party operate. switches direct" lated translation of'th e feature could, however, be retainedfor nor.- mal connections and could then be cut out by the operation of relays 500, 501 or 502. For connections tothe special exchanges it would hardly be desirable to include it, as it would be essential for switching not to take place until the discriminating impulse, it any, had been sent to the connector.

A. slight modification which might be employed with advantage incertain cases makes use of the principle of grading according to which the contacts giving later choices in some of .the levels are n'iult-ipled together. Gonsider the switch E for example; it might be arranged with only one set of wipers and so that instead of levels 2 and 7,- say, leading to second selectors andconuectorsof the same group as previously proposed, the first 5 con-.

tacts in each level led to different groups oi connectors each of standard type, while the last 5 contacts where multipled together and led by Way, of second selectors'to large capacity connectors similar to H in Fig. 6. In this case it is clearly not eccssary to translate the first numerical digit, but it may be sent out exactly as received. Obviously also the discriminating impulse would only be required if one of the last 5 contacts was reached; however as there would be no means of notifying this at the sender the discriminating impulse would beseut out in all cases in which the first numerical. digit was ("l-0 and it it was not required it would do no harm.

The arrangement just described, gives a group of 15 trunks leading in one direction, and this number may be varied slightly by altering the number of multipled contacts.

In case a much larger group were required however, it might be desirable tomake the first selector with two sets of wipers and two separate banks. Simultaneous would then take place vover both banks in each of which grading would be employed telephone number, a sending device in said register sender controlled in accordance with the instant position of the registering apparatus to transmit a translated number representedby series of switch control impulses, and means insaid register sender also con trolled in accordance with the position of the registering apparatus tor transmitting o fimpulse's. i

In a multi-oifice telephone system emswitching currents in addition to said series J- hunt-mg I the oflice designations ot' calledlines into,

series of similar impulses which may dider'in number and value from the original/impulses, means in the register trai'islators whereby the series of stepping impulses representing the. numerical designation of the called line are translated into a combination of stepping impulses and switching currents.

4. In a telephone system as :claimedin claim-3, means in the register translators whereby the translation of the numerical designation of called lines is effected responsiveto calls destined'for certain predetermined offices.

5. In a multi ol'lice telephone system employing register translators for translating series of stepping impulses corresponding to the ofiice designations o1 called lines into serles of similar impulses Wl11Cl1 mayditl'er mnumber and value lrom the original impulses, means in. the register translator whereby the series of stepping impulses representing the numerical designation ofthe' called line are translated'into a combination of stepping impulses and switching currents,

means in the register translators whereby the translation of the numerical designation of called lines is effected responsive to calls destined for certain predetermined oliices, and

means includinga switching relay operated in response to the setting of the ofiice indieating portion of the registe apparatus to indicate certain called o'lficesiior bringing about the said operatiouot said translating means. I V I g I .16. In an automatic telephone system em ploying register senders, for controlling the operation of the automatic switches means associated withthe register-senders in one oilice and responsive to setting of theregistermg portion of the register send ers, to a pos1-' tion correspond ng to a particular.other'ot-.

fice forpreventing the retransmission of one ofthe digits of the numericaldesignation stored on'the registering portion-of the register senders.

7. In an, automatic telephone systemenu ploying register senders controlled over ea-lling lines and employing large capacity step;

by-step switches having (a plurality of sets of wipers each and being controlled bythe register senders, means for, operating the registering portion Oif tl'le register senders to record digits in thenumeric'al des gnations correspond to the reduced number of switches made possible owing tothe fact that the switches of the large capacity type are used,

and for effecting wiper selection predeter p a tered 0n the digit register. 7

. minedones of said switches.

8. In a telephone system, a thousandsselector having a single unitary bank of contacts, a register senderoperated in accord ance with either of ten different digits toset the thousands selector in either of five'dif ferent positions, a set of wipers for 'SELlCl switch having a -f-ree hunting movement over any one of five of the levels of-ih associated bank, depending upon the .pos1-' j tion in. which the switch is set, 'an alternate set of wipers for said SWItGh similarly having a? free hunting movement'- over any one of the other five levels of the associated bank, a switching relay for disconnecting the normal set of wipers and for connecting-up the alternate set ofw1pers,'andmeans for op crating said switching relay or not, depending upon the busy-for idle CODChiLlOIlQOf the trunk lines encountered by the two sets of wipers;

9.In a telephone system,-a four-thousand. line ofiice containing hundreds selectors and connecto'rs, trunk lines. incoming to said office and terminating in Said hundreds selectors, two sets of wipersfor said'hundreds selectors and-two sets of wipers for sa d connectors, means for operating a hundredsselector in accordance with thercorresponding lectorand at the connector in accordance withthe thousands digit in'the said telephone number. e e V 10. In a director for automatic telephone systems, an oflice register, digit register, a locking relay operated when the office register 18 me position corresponding to a certain ofiice, and meanscontrolled by the locking relay for preventing the retransmission of one of the digits registered on the digit register.

11. Ina director for automatic telephone systems, an office register,adigitregister, a

locking relay operated when the oifice regis ter is in a position corresponding' toa certain oflice, and means controlled by the for transmitting switching current,

12. In a director for automatic telephone systems, an office register, a digit register,fa locking relay operatedwhen the oilicev regis ter is in a position corresponding to a certain oflice,'means controlled'by the relay for pre-.

locking relay operated when the officerege ay Venting the retransmission' oi one of the digits registered on'the digit registerandineans controlled by the relay for transmitting switching current. i

1 13. In a director forautomatic telephone systems, an office register, a digit register, a'

locking relay operated when the ofiice register is in a position corresponding to a certain office, and means controlled by the relay for altering the Value ofone-of the digits regis- 14. In a director for automatic telephone i systems, an ofiice 'register,a digit register, a locking relay operated when the office regis-, t'er'isin a position corresponding to a certain oflice, means controlled by the relay'for a1- terin'g the Value of one of the digits registered on the digit register, and means controlled by l j therelay for transmitting switching current.

15. Ina director for automatic teleph systems, an ofiice register, adigit register, a locking relay operated when the office register is in a position corresponding-to a certain ofiice, a'second locking relay operated when the ofiicei register is in aposition cor--.

responding to a certain other flice, 'mean s.

controlled by the first. relay for preventing theretransmissionof one of the digitsreg j; istered on the digit register, and means con.- trolled by the second relay for altering the value of one of the digits registered onthe digit register.

16. In a director forautomatic'telephone I systems, an office register, a digit register, a

ister is in aposition correspondingto a: certain .oitice, a second locking relay operated when the 'ofiice register-is in-a position corresponding to another oiiice, means controlled by the first relay for preventing the retransaltering the'value of'one of the 'digitsregistered. on the digit register.

17. Ina director-for automatic telephone isteris in a position corresponding to a oer-.-

mission ofoneoi the'digits registered on the d1g1t reg1st'er,meanscontrolled by the first systems, an ofiice register, a digit register, -'a locking relay operatedwhen the office reg tain ofiice, a second locking relay operated when the ofiiceregister is in a position corresponding to another ofli'ce, means controlled by the first relay for preventing theretransmissionof one of the digitsregistered in the digit register, and means controlled by the,

rent.

18. In a director for automatic, telephone systems, an oflice' register, a digit register, a j locking relay operatedwhen the'oflice register, 1 I s1napos1t1on corresponding to a'certain second relay for transmitting switching cur-'3 .joi ficeya locking relay operated'when the oilice and means etl'ectire responsive to the relay for preventing the retransmis ion of one of the digits registered on the digit, register, means controlled by the first relay for transmitting switching current, andmeans controlled by the second relay for transmitting switching); current.

19. In a dii or for automatic telephone systems, an office register, digit register, and a loching relay co trolled in accordance with certain setting oi the office register for changinp 'tho value of certain settings of the digit register.

20. In an automatic telephone system, a register sender in one otlice, a plurality of other oilices, means for operating the register sender to store and retransmit groups of digit-impuls aid groups representing both the ofiice' and the rmrticular station in the office to which connection is to be set up,

of the registering: portion oi the register sender to a position corr spending to a particular one oil 1e other oliices, for preventing the retransmi on of one oi? the stations indicating digits stored 21. In a register sender, an office register, a digit register, an impulse transmitter, and

means dependent upon the particular setting of both the otilce reglster and the digit register for transmitting switching current in addi the o'l'lice registerand the digit register tor transmitting switching current in addition to the impulses, and'means de endent upon the particular setting of the oince register and independent of the particular setting or the digit register for absorbing one of thedig'its, 1

23. Inv an automatic telephone system, a

large capacity oiiice, a small capacity o'l'i'ice,

means for extending a connection to a station in either olfice from a third oifice, said means including a register sender having an oince register, a digit register, means'for transmitting; digitscorresponding to the settings of.

both the oflice and the digit registers, and

means in the register sender reflective only if thesmall capacity ofliee is called tor absorbing one of the digits 0n the digit reg1ster.

24.1n an automatic telephone system, a

large capacity oiiice, asmall capacity ofiice,

means for extending a connectionto astation setting of the digit register, for transmittingserics switching current in addition to the or nnpulses.

25. In a telephone system, a switch having;

two sets of wipers, a trunk line incoming to said'switch, and a wipenswitching relay nor-' mally operated over said trunk line responsive to the seizure of the switch. I

26. Inat telephone system, a switch having;- two sets of wipers, a trunk line incoming. to

said switch, a wiper-switching relay normally operated over said trunk line responsive'to the seizure of the switch, and means for grounding a conductor of said trunk line prior to the seizure of said switch to prevent place. I

the operation 0i said relay when seizure takes 27. In a telephone system, a switchihavingtwo sets of wipers, a telephone line inconiing t0 the sw1tch,-and a w1per-sw1tclnngrelay normally connected to one of the conductors ofsaid'llne.

" Signed by IE0 at London, England this 29th day of July, 1924:. r r 'RICHARD lVl'ERGER. A

T Signed by me at London, Englandthis 29th day of July, 1924:. I i v FRANK TENCH. 

